In transportation systems for fluids under pressure, the leakproof link between rigid metal tubes, or between a metal tube and the various openings of the devices in the system, is generally carried out with flanged connections. One type of flanged connection comprises an inside-shouldered nut which is fitted onto one of the tubes to be connected, with the nut being enclosed by the flange on the tube. A threaded adapter on the other tube receives the nut. A gasket is arranged in a ring-shaped groove on the front face of the adapter to provide a leakproof connection with the first tube.
The threaded adapter (which is part of the second tube) typically has a generally cylindrical shape, with an inner shoulder to receive the end of the second tube and an outside threaded portion. The threaded adapter is assembled to the second tube such as by brazing.
In order to carry out an assembly by brazing, it is necessary to prepare the parts to be assembled. These pans must be cleaned, degreased and polished to allow satisfactory adhesion of the filler metal. Then, for the actual brazing, it is necessary to heat the parts and to melt the brazing wire or the brazing ring. Following this operation, the brazed parts are cleaned and the brazing is inspected. All of these operations can be time consuming and expensive.
Also, it can be difficult to braze pans which have been treated against corrosion. This can be very inconvenient when the fluids being transported are corrosive fluids.